Composite medium gate photosensitive detector capable of realizing global shutter in multi-window mode

Abstract

The application discloses a composite medium grating photosensitive detector capable of realizing global shutter in a multi-window mode and belongs to the field of digital circuit design. Grouping is performed on a pixel array of the composite medium grating photosensitive detector, N+1 sets of parallel independent column readout circuits are configured for N groups of pixel arrays, and connection switches are ingeniously arranged so that, in a multi-window opening mode, two sets of parallel column readout circuits simultaneously read out the same window, the maximum exposure time difference is greatly reduced, and further, exposure differences between different rows are eliminated through a differential circuit or a programmable gain module, so that the composite medium grating photosensitive detector can simultaneously capture picture information in the multi-window mode, instability generated during shooting is weakened, and the imaging effect of global shutter is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to a composite medium gate photosensitive detector capable of realizing global shutter in multi-window mode, and belongs to the field of digital circuit design. BACKGROUND

[0002] Shutter is a key component in a camera for controlling the duration of light exposure on a photosensitive element (such as film or CMOS), and its opening and closing time determines the exposure amount. According to different working principles, the shutter can be divided into two types: rolling shutter and global shutter. The rolling shutter exposes the pixels on the photosensitive element row by row or column by column, while the global shutter exposes all the pixels on the photosensitive element at the same time.

[0003] Although the rolling shutter is widely used in modern cameras, its row-by-row or column-by-column scanning mechanism also brings some obvious disadvantages, especially in dynamic scenes or specific lighting conditions. The specific manifestations are as follows: ① Dynamic deformation (distortion): When shooting high-speed moving objects or when the camera moves quickly, the slight difference in recording time of different parts of the picture due to the row-by-row exposure of the sensor will cause the shape of the object to be distorted. For example, a rapidly rotating propeller may appear as a curved "S" shape, and a vertically sweeping object (such as a speeding train) may appear tilted. ② Jello effect: If the camera itself is shaken violently (such as hand-held running shooting), the delay of row-by-row exposure will cause the picture to have a flexible shaking similar to jelly; this phenomenon is particularly obvious in drone aerial photography or action cameras, affecting the visual stability. ③ Flicker banding: Under artificial light sources (such as LED lights, fluorescent lights), the frequency of the light source may not be synchronized with the scanning frequency of the rolling shutter, causing the picture to have alternating bright and dark stripes; for example, when shooting indoors, some areas may become dark because the light source is in the "off" period. ④ Local distortion of fast-moving objects: High-speed moving objects (such as tennis balls, flying birds) may be locally stretched or compressed in the image, especially at the edges of the picture; for example, a car moving quickly across the screen may have different synchronization of blurring at the front and rear due to the time difference in scanning. ⑤ Flash synchronization limitation: When using a flash, the rolling shutter needs to accurately synchronize the flash time with the sensor scanning process; if the flash duration is shorter than the shutter scanning time, only part of the picture may be illuminated (such as only the upper half is bright). Therefore, complex high-speed synchronization technology is needed, which increases the cost and difficulty of operation. ⑥ Inadaptability to high-speed scenes: In the field of professional photography (such as sports, action movies), the distortion problem of the rolling shutter may affect the realism and detail capture of the picture; for example, a golf club may appear soft when it is swung, reducing the visual impact.

[0004] Global shutter has the advantage of capturing the light information of the whole picture at the same time, avoiding the deformation problem when shooting high-speed moving objects. This feature makes it have a significant advantage in certain scenes. The Chinese invention patent with the publication number CN102938409A proposes a composite medium grid photosensitive detector. The feature of this detector is that a single semiconductor device can realize complete reset, photosensitive and readout functions, and constitutes a complete pixel, which can greatly improve the fill factor of the pixel. This composite medium grid photosensitive detector has become a new generation of imaging device due to its faster working speed, larger fill factor, more full well charge and integration with CMOS process. However, the shutter mode it uses is a rolling shutter, and the configuration of reset, photosensitive and readout functions is realized by a strobe module combined with the timing of the rolling shutter.

[0005] Considering the advantages of global shutter over rolling shutter, it is necessary to study the implementation of global shutter for the above-mentioned composite medium grid photosensitive detector. However, due to its simplified single-tube small pixel characteristics, it cannot achieve the separation of readout area and exposure area by setting a transfer node behind the exposure transistor as in the CIS photosensitive detector. At the same time, it also cannot meet the high time accuracy requirement of mechanical shutter, so there is still no effective solution for global shutter of composite medium grid photosensitive detector. SUMMARY

[0006] In order to realize the global shutter scheme of the composite medium grid photosensitive detector and further broaden its application field, the present application provides a composite medium grid photosensitive detector capable of realizing global shutter in multi-window mode, which comprises a pixel array of the composite medium grid photosensitive detector, a row drive circuit, multiple sets of parallel independent column readout circuits and a signal post-processing circuit. The pixel array is divided into N groups with 512 rows as a period, and a set of independent parallel column readout circuit is arranged between each group. Correspondingly, N+1 sets of parallel independent column readout circuits are arranged. The drain terminals of each pixel in the same group of pixel array are connected to the column direction bit lines, and a switch is arranged between the column direction bit lines of the first 256 rows of pixels and the last 256 rows of pixels in each group. The column readout circuits between two groups are connected to the two groups of pixel arrays through a switch respectively. The selection of the switch enables each window to use two sets of column readout circuits for readout at the same time.

[0007] Optionally, the signal post-processing circuit is a non-correlated double sampling differential circuit or a gain module.

[0008] Optionally, the first 256 rows of pixels in the first group of pixel array are directly connected to the first set of parallel independent column readout circuit; and the last 256 rows of pixels in the Nth group of pixel array are directly connected to the first set of parallel independent column readout circuit.

[0009] Optionally, the column readout circuit can select the upper 512 row area, the lower 512 row area or the upper 256 row area plus the lower 256 row area to read out through a switch.

[0010] Optionally, the column readout circuit comprises a reset tube, a clamping circuit module, an integration capacitor, a counter and a comparator, wherein the clamping circuit module is composed of an amplifier and a transistor.

[0011] The application also provides an exposure imaging method of the composite medium gate photosensitive detector capable of realizing global shutter in a multi-window mode, which is realized based on the composite medium gate photosensitive detector and the signal post-processing circuit is a non-correlated double sampling differential circuit, and the method comprises the following steps:

[0012] Step 1: according to the window opening coordinates of each window, the multi-window is allocated with a readout circuit, so that each window utilizes two sets of column readout circuits to read out simultaneously;

[0013] Step 2: according to the number of rows corresponding to the window opening coordinates of each window, the row state machine register corresponding to the rows is configured and set to a to-be-read-out state;

[0014] Step 3: according to the row grouping mode of the pixel array, the row state machine register of the first row pixel in each group set to the to-be-read-out state is synchronized to start the working time sequence, and the working time sequence is controlled by the row driving circuit applying different voltages to the row word line to excite; the working time sequence is divided into a reset phase, an exposure phase and a readout phase; the row driving circuit applies a negative bias voltage smaller than the substrate voltage in the reset phase, applies zero bias voltage in the exposure phase and applies a ramp voltage signal in the readout phase, and the readout is performed in cooperation with the column readout circuit;

[0015] Step 4: after the readout time of the first row in each row group ends, the row state machine register of the second row pixel set to the to-be-read-out state in each group is synchronized to start the readout, and the working time sequence of the second row is the same as that of the first row;

[0016] Step 5: after all rows are synchronized to complete the reset, the exposure is started synchronously, and the exposure and readout of the row pixel signal of all row state machine registers set to the to-be-read-out state are completed in sequence, and the readout result is taken as the bright field sampling result DN Bright in global shutter non-correlated double sampling;

[0017] Step 6: the row pixel with the row state machine register set to the to-be-read-out state is read out again in the manner of steps 2 to 4, but the exposure time of the first row is set to the shortest exposure time, all rows are synchronously exposed, and the readout is performed in sequence, and the readout result is taken as the dark field sampling result DN Dark in global shutter non-correlated double sampling;

[0018] Step 7, calculate DN in the non-correlated double sampling differential module Bright -DN Dark , and the calculation result is the final global exposure window data output off-chip.

[0019] The application further provides another exposure imaging method of the composite medium gate photosensitive detector capable of realizing global shutter in a multi-window mode, which is realized based on the composite medium gate photosensitive detector and the signal post-processing circuit is a gain module, and the method comprises the following steps:

[0020] Step 1, assign readout circuits to the multi-windows according to the window opening coordinates of each window, so that each window is read out by using two sets of column readout circuits at the same time.

[0021] Step 2, configure the row state machine register in which the corresponding row is located according to the number of rows corresponding to the window opening coordinates of each window, and set it to a to-be-read-out state.

[0022] Step 3, according to the row grouping mode of the pixel array, the row state machine register in each group is set to the first row of pixels in the to-be-read-out state, and the working timing is started synchronously; the working timing is controlled by applying different voltages to the WL of the row by the row driving circuit, and is divided into a reset phase, an exposure phase and a readout phase, the reset phase is given a negative bias voltage smaller than the substrate voltage by the row driving circuit, the exposure phase is given a zero bias voltage, and the readout phase is given a slope voltage signal, and the column readout circuit is read out in cooperation.

[0023] Step 4, all rows are reset synchronously and start exposure synchronously, after the readout time of the first row in each row group ends, the row state machine register in each group is set to the second row of pixels in the to-be-read-out state, and the working timing of the second row is the same as that of the first row, all rows are reset synchronously and start exposure synchronously.

[0024] Step 5, multiply the readout result by a coefficient k in the programmable gain module, and the calculation result is the final global exposure window data output off-chip; the value of k set for each row is calculated as follows:

[0025]

[0026] wherein, N is the number of rows, k is the coefficient multiplied by each row, T is the exposure time, read T is the readout time of each row.

[0027] The application has the following beneficial effects:

[0028] By grouping the pixel array of the composite medium gate photosensitive detector, configuring N+1 sets of parallel independent column readout circuits for N groups of pixel arrays, and skillfully setting the connection switch to enable two sets of parallel column readout circuits to read out at the same time in the multi-window opening window mode, the maximum exposure time difference is greatly reduced, and further through the differential circuit or programmable gain module, the exposure difference between different rows is eliminated, so that the picture information under the multi-window can be captured at the same time, the instability generated during shooting is weakened, and the application of the present application to scenes with high time resolution, especially when shooting high-speed motion or fast-moving scenes, can better ensure the shooting quality and solve various problems caused by the rolling shutter exposure mode. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0030] Figure 1 The pixel array schematic diagram of the composite medium gate photosensitive detector in the embodiment of the present application.

[0031] Figure 2 The readout circuit schematic diagram in the embodiment of the present application.

[0032] Figure 3 The row drive circuit schematic diagram in the embodiment of the present application.

[0033] Figure 4 The overall step block diagram of realizing the multi-window opening window mode global shutter.

[0034] Figure 5 The row-by-row working timing operation schematic diagram.

[0035] Figure 6 The circuit diagram of one implementation of the non-correlated double sampling differential module.

[0036] Figure 7 The circuit diagram of one implementation of the gain module circuit.

[0037] Figure 8 The corresponding windowing schematic diagram in the present application scheme. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the present application more clear, the embodiments of the present application will be further described in detail below with reference to the drawings.

[0039] Embodiment one

[0040] The embodiment provides a composite medium gate photosensitive detector capable of realizing global shutter in a multi-window mode, which comprises a pixel array of the composite medium gate photosensitive detector, a row driving circuit, a plurality of sets of parallel independent column readout circuits and a signal post-processing circuit; wherein the pixel array of the composite medium gate photosensitive detector is divided into N groups with 512 rows as a period, corresponding to N+1 sets of parallel independent column readout circuits; the drain ends of each pixel in the pixel array in the same group are connected to column-direction bit lines (BL), and a switch is arranged between the column-direction bit lines of the first 256 rows of pixels and the last 256 rows of pixels in each group; one set of independent parallel column readout circuits is arranged between the groups; except the first group and the last group, the first 256 rows of pixels and the last 256 rows of pixels in each group of pixel arrays are connected to two sets of independent parallel column readout circuits on both sides through a switch; the first 256 rows of pixels in the first group of pixel arrays are directly connected to the corresponding column readout circuit, the last 256 rows of pixels are connected to the corresponding column readout circuit through a switch, the first 256 rows of pixels in the last group of pixel arrays are connected to the corresponding column readout circuit through a switch, and the last 256 rows of pixels are directly connected to the corresponding column readout circuit.

[0041] As shown in Figure 1 , two groups of pixel arrays correspond to three sets of parallel independent column readout circuits Read1, Read2 and Read3, and the column readout circuit corresponding to each column of pixels is of the same structure, Figure 1 , wherein one set of column readout circuits is shown in a block.

[0042] In each group of pixel arrays, the drain ends of the first 256 rows of pixels are connected to column-direction bit lines, the drain ends of the last 256 rows of pixels are connected to column-direction bit lines, and a switch (such as the switches S1 and S4 in Figure 1 ) is arranged between the column-direction bit lines of the first 256 rows of pixels and the last 256 rows of pixels; the column-direction bit line of the first 256 rows of pixels in the first group of pixel arrays is directly connected to the column readout circuit Read1, the column-direction bit line of the last 256 rows of pixels is connected to the column readout circuit Read2 through the switch S2, at the same time, the column readout circuit Read2 is also connected to the column-direction bit line of the first 256 rows of pixels in the second group of pixel arrays through the switch S3, the column-direction bit line of the last 256 rows of pixels in the second group of pixel arrays is connected to the column readout circuit Read3 through the switch S5, the column readout circuit Read3 is also connected to the column-direction bit line of the first 256 rows of pixels in the next group of pixel arrays through the switch S6, and so on, the column-direction bit line of the last 256 rows of pixels in the last group of pixel arrays is directly connected to the column readout circuit Read N+1 .

[0043] In this way, the same readout circuit can implement multiple readout schemes, and the upper 512 rows, the lower 512 rows, or the upper 256 rows plus the lower 256 rows can be selected for readout, so that any windowing mode can be read out simultaneously by two sets of readout circuits, thereby accelerating the speed and reducing the maximum exposure time difference between the rows.

[0044] As shown in Figure 2 , the column readout circuit used in the application is an existing circuit, which includes a reset tube Reset, a clamping circuit module, an integration capacitor C int , a counter, and a comparator, wherein the clamping circuit fixes the voltage of BL, i.e., the drain of the pixel, to maintain the readout state unaffected by the current, and the comparator and the counter are used to quantize the read signal to a digital value, and the connection relationship of each part is as shown in Figure 2 ; Figure 2 The clamping circuit module includes an amplifier and a transistor, V RefClamp is the reference voltage of the amplifier, V OS，Clamp and are non-ideal factors in the clamping circuit module, wherein V OS，Clamp represents the offset deviation in the clamping circuit module, represents the noise deviation in the clamping circuit module. V RefComp is the reference voltage of the comparator, V OS，Comp and are non-ideal factors in the comparator circuit, wherein V OS，Comp represents the offset deviation in the comparator circuit, represents the noise deviation in the comparator circuit.

[0045] As shown in Figure 3 , the row drive circuit used in the application is an existing circuit, and each row corresponds to a row drive circuit including a state machine, a level conversion module, and a circuit gating module; the level conversion module is composed of three level converters, and the circuit gating module is composed of MOS tubes; the state machine configures the signal output by the current state to the level conversion module, thereby inputting the voltage to the corresponding port in the circuit gating module, to achieve the function of realizing three different driving voltages for three different pixel states. Figure 3In the embodiment, the EN_READ, EN_EXPO and EN_RST signals output by the state machine are converted into VHH, VL and VLL signals by the level conversion module, and the three signals are input into the circuit gating module to further control the VRAMP (readout mode voltage), Vexpo (exposure mode voltage) and Vrst (reset mode voltage) to output to the WL_SW_OUT port; in the level conversion module, the CHP_5V, CHP_NEG1P6 and CHP_NEG3 level converters input the same clock signal CLK; the LDPMOS1, LDPMOS2, NMOS1, LDNMOS2, OD33NMOS and LDNMOS3 are MOS tubes in the circuit gating module.

[0046] As shown in Figure 4 , the overall steps of the scheme for realizing global shutter in the multi-window opening window mode mainly include setting circuit parameters, allocating readout circuit modes, and setting connection switches to enable two sets of parallel column readout circuits to read out the same window in the multi-window opening window mode, thereby greatly reducing the maximum exposure time difference, and further eliminating exposure differences between different rows through a differential circuit or a programmable gain module, so that the scheme can capture picture information under the multi-window mode at the same time and weaken the instability generated during shooting.

[0047] The signal post-processing circuit in the embodiment is implemented by using the non-correlated double sampling differential circuit shown in Figure 6 , which includes three resistors and an operational amplifier and can achieve the differential function between Data_bright and Data_dark. Other non-correlated double sampling differential circuits that can achieve differential can also be used, and the circuit structure shown in Figure 6 is taken as an example in the embodiment.

[0048] The embodiment takes the case of two windows being opened at the same time as an example to introduce the process of realizing global shutter by the compound medium grating photosensitive detector: each window contains 512*512 pixels, the starting coordinates of window ① are the first pixel point of the first 512-row group of the pixel array of the compound medium grating photosensitive detector, which are (1, 1), and the starting coordinates of window ② are (257, 513), at this time, the 1st to 768th rows need to be read out, and the window opening diagram is as shown in Figure 8 , and the specific steps are as follows:

[0049] Step 1: allocate readout circuits for the two windows:

[0050] Step 1.1: close the middle boundary switch S1 in the periodic group below Read1, at this time, Read1 can read out the pixels in the 256 adjacent rows below.

[0051] Step 1.2, open the switch S2 connected to the upper Read2, close the switch S3 connected to the lower Read2, at this time, the Read2 can read the pixels of the 256 rows above.

[0052] Step 1.3, open the switch S5 connected to the upper Read3 and the switch S4 connected to the middle boundary line in the lower period group of Read2, close the switch S6 connected to the lower Read3, at this time, the Read3 can read the pixels of the 256 rows far above.

[0053] Step 2, according to the row number corresponding to the windowing coordinates, configure the row state machine register corresponding to the row, and set it to the state to be read out;

[0054] Step 3, according to the row grouping mode of the pixel array, the first row pixel in each group whose row state machine register is set to the state to be read out starts to work synchronously, the working timing is controlled by the row driving circuit applying different voltages to the row word line (WL) to excite, which is divided into a reset phase, an exposure phase and a readout phase, the reset phase is given a negative bias voltage less than the substrate voltage by the row driving circuit, the exposure phase is given a zero bias voltage, and the readout phase is given a ramp voltage signal, which is read out by the column readout circuit;

[0055] Step 4, after the readout time of the first row in each row group ends, the second row pixel in each group whose row state machine register is set to the state to be read out starts to read out synchronously, and the working timing sequence of the second row is the same as that of the first row;

[0056] Step 5, after all rows are reset synchronously, exposure starts synchronously, and the exposure and readout of the row pixel signal of all rows whose row state machine register is set to the state to be read out in each row group are completed in sequence, and the readout result is taken as the bright field sampling result DN Bright in the global shutter non-correlated double sampling;

[0057] Step 6, the row pixel whose row state machine register is set to the state to be read out is read out again in the manner of steps 2 to 4, but the exposure time of the first row is set to the shortest exposure time, all rows are exposed synchronously, and the readout is performed in sequence, and the readout result is taken as the dark field sampling result DN Dark in the global shutter non-correlated double sampling;

[0058] Step 7, DN Bright -DN Dark is calculated in the non-correlated double sampling difference module, and the calculation result is the final global exposure window data output off-chip.

[0059] In combination with the case of two windows in the embodiment, it is assumed that the readout time of one row of pixels is T read , and Figure 5It can be seen that the exposure time difference between the first row and the nth row in the row read by the same readout circuit is (n-1) x T read , and the maximum exposure time difference will reach 767 x T read for two windows in this embodiment, while it can be reduced to 255 x T read after using the pixel array and exposure timing described above in this embodiment, greatly reducing the maximum exposure time difference.

[0060] In this embodiment, a non-correlated double sampling differential circuit is used as a signal post-processing module. The differential circuit can reduce the signal increase due to the additional exposure time of the later read row compared to the earlier read row caused by simultaneous exposure, thereby further reducing the adverse effects of the rolling shutter exposure mode and achieving the effect of global exposure.

[0061] Embodiment Two

[0062] This embodiment provides a composite medium grating photosensitive detector that can realize global shutter in multi-window mode, which includes a pixel array of a composite medium grating photosensitive detector, a row drive circuit, multiple sets of parallel independent column readout circuits, and a signal post-processing circuit. The descriptions of the components are the same as in Embodiment One, except that the signal post-processing circuit in this embodiment is implemented using a programmable gain module as shown in Figure 7 .

[0063] As shown in Figure 7 , the programmable gain module includes three resistors, an adjustable resistor Rt, and an operational amplifier. The gain adjustment of the input signal can be achieved by adjusting the adjustable resistor Rt, Figure 7 only one implementation of a programmable gain module is given, other circuits that can achieve gain adjustment of the input signal are also possible, and the present invention does not limit this.

[0064] This embodiment also takes the simultaneous opening of two windows as an example to introduce the process of the composite medium grating photosensitive detector realizing global shutter: each window contains 512 x 512 pixels, the starting coordinates of window ① are the first pixel point of the first 512-row group of the pixel array of the composite medium grating photosensitive detector, which is (1, 1), and the starting coordinates of window ② are (257, 513). At this time, the 1st to 768th rows need to be read out, and the window opening diagram is as shown in Figure 8 , and the specific steps are as follows:

[0065] Step 1, allocate readout circuits for two windows:

[0066] Step 1.1, turn off the middle dividing line switch S1 below Read1 in the periodic group, at this time Read1 can read out the pixels of the adjacent 256 rows below.

[0067] Step 1.2, open the switch S2 connected to the upper Read2, close the switch S3 connected to the lower Read2, at this time, the Read2 can read the pixels of the upper adjacent 256 rows.

[0068] Step 1.3, open the switch S5 connected to the upper Read3 and the switch S4 connected to the middle boundary line in the lower period group of Read2, close the switch S6 connected to the lower Read3, at this time, the Read3 can read the pixels of the upper distal 256 rows.

[0069] Step 2, according to the row number corresponding to the windowing coordinates, configure the row state machine register where the corresponding row is located, and set it to the state to be read out.

[0070] Step 3, according to the row grouping mode of the pixel array, the first row pixel in each group whose row state machine register is set to the state to be read out starts working synchronously. The working timing is controlled by the row driving circuit applying different voltages to the WL of the row. The working timing is divided into a reset phase, an exposure phase and a readout phase. The reset phase is given a negative bias voltage less than the substrate voltage by the row driving circuit, the exposure phase is given a zero bias voltage, and the readout phase is given a ramp voltage signal, which is read out by the column readout circuit.

[0071] Step 4, all rows are reset synchronously and start exposure synchronously. After the readout time of the first row in each row group ends, the second row pixel in each group whose row state machine register is set to the state to be read out starts working synchronously. The working timing of the second row is the same as that of the first row, and all rows are reset synchronously and start exposure synchronously.

[0072] Step 5, multiply the readout result by a coefficient k in the programmable gain module, and the calculation result is the final global exposure window data output outside the chip. The value of k set for each row is calculated as follows:

[0073]

[0074] wherein, is the number of rows, is the coefficient multiplied by each row, is the exposure time, T read is the readout time of each row.

[0075] Similarly, after using the pixel array and the exposure timing described in the embodiment, the maximum exposure time difference is reduced from 767×T read to 255×T read Further, the gain module processing method is used to scale the excess exposure signal of each row to be consistent.

[0076] In the two embodiments of the present application, two windows are taken as examples for introduction. In an actual application scenario, in a multiple-window opening mode, by opening and closing of each switch, each window can be read out by two readout circuits, so that the maximum exposure time difference is greatly reduced. In combination with a differential circuit or a gain module, the adverse effects caused by the roller shutter exposure mode are further reduced, and the effect of global exposure is achieved.

[0077] Some steps in the embodiments of the present application can be implemented by software, and the corresponding software program can be stored in a readable storage medium, such as an optical disc or a hard disk.

[0078] The above description is only the preferred embodiment of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A compound medium gate photodetector capable of global shuttering in multi-window mode, characterized in that, The composite medium gate photosensitive detector comprises a pixel array of the composite medium gate photosensitive detector, a row driving circuit, a plurality of sets of parallel independent column readout circuits and a signal post-processing circuit; wherein the pixel array is divided into N groups with 512 rows as a period, and a set of independent parallel column readout circuits is arranged between groups, and N+1 sets of parallel independent column readout circuits are correspondingly arranged; the drain ends of each pixel in the pixel array in the same group are connected to a column direction bit line, and a switch is arranged between the column direction bit lines of the first 256 rows of pixels and the last 256 rows of pixels in each group; the column readout circuits between two groups are connected to the two groups of pixel arrays through a switch respectively; and the selection of the switch enables each window to simultaneously utilize two sets of column readout circuits for readout.

2. The composite interdigitated photodetector of claim 1, wherein, The signal post-processing circuit is a non-correlated double sampling differential circuit or a gain module.

3. The composite interdigitated photodetector of claim 2, wherein, The first 256 rows of pixels in the first group of pixel arrays are directly connected to the first set of parallel independent column readout circuits; and the last 256 rows of pixels in the Nth group of pixel arrays are directly connected to the N+1th set of parallel independent column readout circuits.

4. The composite interdigitated photodetector of claim 3, wherein, The column readout circuit can read out the upper 512 row region, the lower 512 row region or the upper 256 row region plus the lower 256 row region through the switch.

5. The composite interdigitated photodetector of claim 4, wherein, The column readout circuit comprises a reset tube, a clamping circuit module, an integration capacitor, a counter and a comparator, wherein the clamping circuit module is composed of an amplifier and a triode.

6. An exposure imaging method of a composite medium gate photodetector capable of realizing global shutter in a multi-window mode, characterized in that, The method is implemented based on the composite medium gate photosensitive detector of claim 1, the signal post-processing circuit is a non-correlated double sampling differential circuit, and the method comprises the following steps: Step 1, assigning readout circuits to the multiple windows according to the window opening coordinates of the windows, so that each window simultaneously utilizes two sets of column readout circuits for readout; Step 2, configuring the row state machine register in which the corresponding row is located according to the number of rows corresponding to the window opening coordinates of each window, and setting the row state machine register to a to-be-read state; Step 3, setting the first row of pixels in each group for which the row state machine register is set to a to-be-read state to start working synchronously according to the row grouping mode of the pixel array, and controlling the working timing by applying different voltages to the row direction word line of the row through the row driving circuit, which is divided into a reset phase, an exposure phase and a readout phase; a negative bias voltage smaller than the substrate voltage is applied to the row in the reset phase, zero bias voltage is applied to the row in the exposure phase, and a ramp voltage signal is applied to the row in the readout phase, and the readout is performed in cooperation with the column direction readout circuit; Step 4, after the readout time of the first row in each row group ends, setting the second row of pixels in each group for which the row state machine register is set to a to-be-read state to start readout synchronously, and the working timing of the second row is the same as that of the first row; Step 5, after all the row synchronization reset, the synchronization starts the exposure and reads out in sequence, completes the exposure and readout of all the row pixel signals in all the row state machine registers in the row group set to the state of waiting for readout, and the readout result is taken as the bright field sampling result DN in the global shutter non-correlated double sampling Bright ; Step 6, re-read the row state machine register set to the row pixels in the readout state, but the first row of the exposure time set to the shortest exposure time, all rows of synchronous exposure, in order to read out, read out results as a global shutter non-related double sampling in the dark field sampling results DN Dark ; Step 7, compute DN in non-correlated double sampling difference module Bright -DN Dark , the result is the final global exposure window data output off-chip.

7. An exposure imaging method of a composite medium gate photodetector capable of realizing global shutter in a multi-window mode, characterized in that, The method is implemented based on the composite medium gate photosensitive detector of claim 1, the signal post-processing circuit is a gain module, and the method comprises the following steps: Step 1, assigning readout circuits to the multiple windows according to the window opening coordinates of the windows, so that each window simultaneously utilizes two sets of column readout circuits for readout; Step 2, configuring the row state machine register in which the corresponding row is located according to the number of rows corresponding to the window opening coordinates of each window, and setting the row state machine register to a to-be-read state; Step 3, according to the row grouping mode of the pixel array, the row state machine register in each group is set to the first row of pixels in a readout state, and the working timing is started synchronously; the working timing is controlled by the row driving circuit by applying different voltages to the row word line WL to excite the row, and is divided into a reset stage, an exposure stage and a readout stage; the reset stage is given a negative bias voltage smaller than the substrate voltage by the row driving circuit, the exposure stage is given a zero bias voltage, and the readout stage is given a ramp voltage signal, and the readout is performed by the column readout circuit; Step 4, all rows are reset synchronously and exposure is started synchronously, and after the readout time of the first row in each row group ends, the row state machine register in each group is set to the second row of pixels in a readout state, and the working timing of the second row is the same as that of the first row, and all rows are reset synchronously and exposure is started synchronously; Step 5, the readout result is multiplied by a coefficient k in the programmable gain module, and the calculation result is the final global exposure window data output outside the chip; the k value of each row is set as follows: wherein, is the number of rows, is the coefficient of multiplication for each row, is the exposure time, T read is the readout time for each row.

Images